where a good place to get my speedometer checked

[redflame22]

I just got 33in tires put on my 05 f150 and trying to find a place to get my speedometer checked ?

[BPofMD]

Much cheaper to use a measured mile(or 5 mile) section of the highway.....

[BPofMD]

More info....After checking my manual, your speedometer gets the speed information from (one of) the front hubs. There is a speed sensor located in the ABS system which gets the vehicle speed info from that front hub ring. So tire size will NOT make a speedometer change.

[redflame22]

Thanks for that info

[Greywolf]

Fly through a virginia speed trap - they'll tell ya exactly what they got ya for...

[HrdDrv]

Is your system RABS? If so, how does it connect to a front wheel assy? Just wunderin'

[fire240]

You could also go to your local state police barracks and tell them you need to have your speedo checked. They will take you out to one of the local highways and have you run up to the speed limit and clock you with radar and let you know what they came up with so you can get it corrected. If I remember correctly it was free. Dan an 05 would have 4 wheel abs.

[HrdDrv]

Gotcha Shaun,
Like I said, just wunderin...

[fire240]

Not a problem Dan.

[arctic y block]

Dutch ya beat me to it. I was thinking that when I read the header in the New Post's

[jr32560]

Originally Posted by Greywolf

Fly through a virginia speed trap - they'll tell ya exactly what they got ya for...

yup this works every time

[MD05]

Learned a great deal this past weekend at the tuning shop...

This is to the Diesel guys but I am fairly sure that it applies to the newer gas rigs as well. Speed is picked off the rear axle (tone ring within) on the 250-550 trucks and wheel size will modify what is seen on the gauge. If it were off the front ABS tone ring the speedo would not indicate an increase in speed when you rear tires slip. My 05 and current 08 indicate wheel spin at the speedo.

Something else to look with electronic transmission programming the power train module does take into account wheel size in it's calculations to adjust /make shift points and timing thereof. This may ( or may not) create issues down the road. With my rig it will cause soem issues with timing of shifts.

[MD05]

A simpler and cheaper idea to check speed:
1. Check based on Miles posts on highway... 60MPH = 1 mile per min.
2. Use a had held GPS and measure ground speed over a fixed distance and speed. Instanttanious measurements are ofter incorrect but if you let it integrate over time say 3-5 minutes you should get a fairly steady reading.

[MD05]

Originally Posted by BPofMD

More info....After checking my manual, your speedometer gets the speed information from (one of) the front hubs. There is a speed sensor located in the ABS system which gets the vehicle speed info from that front hub ring. So tire size will NOT make a speedometer change.

Bud...... Increase in overall diameter will decrease what is displayed on the speedo gauge. It is purely a mechanical thing

While the tone ring is still the same diameter there will be no change to the system input however, the larger tire will travel further with each revolution thus your indicated speed will be slower than actual = a government donation and an accumulation of award points........ Not a good thing and will not hold up in court.

If you take that argument to court it will end up getting you more reward points and another donation for faulty equipment..... Not advisable take my word on that one.

[BPofMD]

I apologize, now that you said it, I do remember that fact. And I should know better.....when I plug in my tuner, it gives me the chance to correct that error if I install larger wheels/tires.

I did tell you about the road markers tho.....